In automotive or marine engines, since a bearing which supports a crankshaft for converting reciprocating motion of a piston into rotary motion is disposed between counterweights or a counterweight and a large end portion of a connecting rod, a split bearing is used which is split into two in a circumferential direction.
Conventionally, while slide bearings have been used as the supporting bearing described above, in recent years, there have been increasing demands for engines which consume less fuel. Due to these increasing demands, it has been proposed to use a bearing which is split in a circumferential direction in place of the slide bearing so as to decrease rotation loss (for example, refer to Patent Document 1).
Patent Document 2 describes an example in which a split bearing is interposed between a crankpin and a large end portion of a connecting rod of an internal combustion engine. This split bearing has a split outer ring which is inscribed in an inner circumferential surface of the large end portion of the connecting rod and a plurality of rollers which are disposed rollingly between an inner circumferential surface of the split bearing and an outer circumferential surface of the crankpin. The split outer ring is configured so as to be split by combining together a pair of split outer ring members which are each formed into a substantially semi-cylindrical shape. The split bearing can be split in a radial direction by employing the split outer ring which can be split apart and can be assembled to an outer circumferential side of the crankpin which is offset with respect to a rotating axis of a crankshaft.
Since the pair of split outer ring members are butted against each other at circumferential end portions thereof, there is a fear that an alignment error is caused as a result of the split outer ring members moving in an axial direction relatively to each other. Because of this, an angular projecting portion which projects in the circumferential direction is formed at one end portion, and a V-shaped recess portion which corresponds to the projecting portion is formed at the other end portion of the circumferential end portions which are butted against each other, whereby the axial relative movement of the pair of split outer ring members is prevented by those projecting portion and the recess portion being brought into engagement with each other.
In addition, in the split rolling bearing, while the circumferential end faces of the set of two split outer rings are brought into abutment with each other to form a mating surface, there may occur a radial alignment error between the facing end portions of the outer rings at the mating surface due to an assemblage error of the rolling bearing to a housing which has a supporting hole where the rolling bearing is accommodated or the worked condition of a fitting surface of the housing. As a result, there may occur a case where a level difference which projects radially inwards is formed at the mating surface.
Then, as is shown in FIG. 17, in the event that a level difference 75 is produced in a radial direction (a vertical direction in FIG. 17) at a mating surface C between split outer rings 72a, 72b, when a roller 73 rolls near the mating surface C between the split outer rings where the level difference is being produced, a circumferential surface of the roller 73 is brought into collision with a corner 75a of the level difference 75, there being caused a fear that noise or vibration is generated.
Then, in order to suppress noise or vibration which would be caused in association with the passage of the roller over the level difference, it is proposed to form a “recess” or “flank” by setting back a raceway surface of the outer ring lying near the mating surface radially outwards (for example, refer to Patent Document 3).
In the bearing described in Patent Document 3, the V-shaped projecting portion is provided at the circumferential end portion of the one outer ring and the V-shaped recess portion is provided at the circumferential end portion of the other outer ring, the circumferential end portions forming the mating surface. Inclined surfaces (flanks) are formed on an inner circumferential surface side of each of the outer rings, which constitutes an outer ring raceway surface, at the respective circumferential end portions thereof so as to be inclined in a direction in which a radial thickness is gradually decreased towards circumferential distal-end edges of each of the outer rings. According to the bearing described in Patent Document 3, it is said that even in the event that a radial alignment error is generated at the mating surface of both the outer rings, the generation of a level difference can be prevented by the formation of the inclined surfaces, as a result of which the generation of noise or vibration is suppressed.